import java.util.*;
public class Main
{
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        char[] s = in.next().toCharArray();
        int n = s.length;

        boolean flag = false;
        for(int i = 1; i < n; i++) {
            if(s[i] != s[0]) {
                flag = true; break;
            }
        }

        if(flag == true)  {// 不是相同的字符
            flag = false;
        // 判断本⾝是不是回⽂
        int left = 0, right = n - 1;
        while(left < right) {
            if(s[left] == s[right]) {
                left++; right--;
            } else {
                flag = true;
                break;
            }
        }
        if(flag == true)
            System.out.println(n);
        else
            System.out.println(n - 1);
        } else{// 是相同字符
         System.out.println(0);
        }
    }
}

